1. Field of the Invention
The present invention relates generally to heat flux gauges and methods of producing heat flux gauges, and more particularly to plug-type heat flux gauges having thermoplugs that are integrally formed into a specimen material and methods for producing same.
2. Description of the Related Art
Recently, there has been increasing need for small, reliable, accurate and easily built heat flux gauges. For example, heat flux gauges are needed to obtain transient and steady-state surface heat flux data for verification of models relating to heat transfer, durability and aerodynamics. In many applications, heat flux gauges are required to be accurate over wide ranges of heat flux values that vary over wide temperature ranges. For example, in order to obtain rapid transient surface heat flux measurements on turbine blades utilized in spacecraft, a heat flux gauge may be required to provide accurate measurements for surface heat flux values varying from about 0.3 to 6 MW/m.sup.2 over a temperature range of 100 to 1200K.
Water-cooled heat flux gauges are available for measurement to about 10 MW/m.sup.2, but only at surface temperatures that are maintained between 280 to 360K. Also, water-cooled heat flux gauges tend to be relative large, e.g., often greater than 2.0 cm in diameter and length. Thus, because of their relatively large size and narrow temperature range, water-cooled heat flux gauges often cannot be used.
Another type of heat flux gauge is the plug-type heat flux gauge. Typically, plug-type heat flux gauges include a thermoplug that is screwed or welded into a specimen material having an active surface, creating a seam between the active surface and the thermoplug. This seam can introduce large discontinuities in surface temperature, resulting in very large errors in heat flux measurement. It is extremely difficult to determine the uncertainty in the resulting heat flux measurements due to the seam. Thus, the lack of accuracy and precision of conventional plug-type heat flux gauges may prohibit their use.